Aeroplane construction.



M. G. KRARUP.

AEROPLANE CONSTRUCTION. APPLICATION FILED JUNE 16, 1910.

2 SHEETS-SHEET 1.

2g N I k I! |l l I WITNESSES: 1 INVENTOR ATTORNEY M. G. KRARUP.

AERQPLANE CONSTRUCTION.

APPLIOATION FILED JUNE 16, 1910.

1,124,917, I PatentedJan.l 2,l9 l' 5.

I 2 SHEETS-SHEET 2.

WITNESSES:

Mnnros c. KrLAnur, or NEW YORK, N. Y.

nnnornann coivsr'noomrom.

. maaerz.

Application filed June 16, 1910. Serial No. 567,163.

To all whom it may concern:

Be it known that I, MARIUS C. KRARUP, a citizen of the United States,and a resident of the borough of Manhattan, in the city, county, andState of New York, United States of America, have invented certain newand useful Improvements in Aeroplane Constructions, of which thefollowing is a specification.

My invention relates to aeroplane constructions and especially to thoseparts of apparatus of this kind which form air resistance surfaces. I

Its object is'to improve upon aeroplanes by so constructing some oftheir parts that their efliciency will be increased.

I will describe my invention in the following specification and pointout the novel features thereof in the appended claims.

Referring to the drawings, Figure 1 is a side elevation of a well-lmowntype of aeroplane constructed in this case to embody my invention. Fig.2 is a side elevation of the propeller on a somewhat larger scale,showing its front and rear surfaces. In Fig. 3 I have shown in invertedplan view on an enlarged scale, one of the planes or wings of theapparatus which is shown in Fig. 1. Fig. 4 is-a sectional side elevationof the plane shown in Fig. 3, the section being taken on the line 44 ofthe latter figure. Fig. 5 shows a detail of construction. This figure isa sectional front elevation on'the line 5-5 of Fig. 3, showing one ofthe ribs of the frame and a manner of afixingcertain parts thereto. Fig.6 shows in sectional side elevation a modified form of my invention. InFigs. '1 and 8 I have shown in inverted plan view and in sectional endelevation, respectively, a still further modification.

. Like characters of reference designate corresponding parts in all ofthe figures.

10 designates an aeroplane of a wellknown biplane design. This is shownbut diagrammatically in the drawings, and for the sake of clearness someof its parts are omitted as it forms no part of the present invention.11 is its motor and 12 its propeller. The planes are designated by .13,13, and 14 are the skids which support it when on the ground.

The planes and some of the other parts of the apparatus are used forapplying a thrust against the atmosphere. Heretofore they have beenprovided with plane or concave surfaces so shaped that the atmosphere inits movement relative to the surfaces met no obstacles or rugosities.These devices have been set at a small angle of incidence with the mainextension of their pressure surfaces for the purpose of obtaining aSpecification bf Letters Patent. Patentedan, 12, 1915,.

thrust at substantially right-angles to the direction of motion. Ifthepressure surfaces were plane or nearly plane, and the angle ofincidence small, such as from 0 to 15, the thrust was small inproportion to the velocity employed, but the resistance'to motion wasalso small. If the pressure surfaces were hollow under otherwise similarconditions, the thrust became greater, but

the resistance to motion grew at a much more rapid rate than did thethrust. When the parts which form these surfaces are made according tomy invention, a much increased thrust is obtained with only a slightlyincreased resistance to motion.

Referring now to Fig. 3 I will explain a construction of planes whichembodies my invention. In the front of the frame is a substantiallyrigid spar 20. 21 is a parallel member which forms the rear of theframe. These two parts are connected by a plurality of ribs 22. Thus alight rigid frame is built up over the top of which is stretched curelyfastened to the different parts of the frame. Instead of covering theunder side of the frame with similar material ll leave it downward fromthe under surfaces .of the cover 23. Narrow strips or ribbons 24 of thintextile webbing or other suitable material projecting edgewise from thecover 23 are affixed to the front and rear of the frame and secured atintervals to the ribs preferably in such a manner that they crossobliquely to and from one rib to the next. Battens may be used to securethesestrips to the ribs, or flat wires 25 may be used for open so thatthe parts of the frame project this purpose; or any other suitablefastening may be used. Their upper edges should also be stitchedor'otherwise secured to the cover 232 Thus the under surface ofthe planeor its pressure surface is divided into a plurality of shallowtriangular air pockets,

while its upper surface is made smooth as in former practice. Thesepockets are not necessarily of uniform depth but are preferably madewith varying depths as is shown in Fig. 4. Neither are they necessarilyin'described have greater consistency in the of equal areas. The stripsmaterially strengthen the structure so that a stronger plane may bebuilt with a given weight than could be made with former constructions.The air pockets thus formed will obviously roduce a greater liftingthrust and ,vwill add but little resistance to the propulsion of theapparatus.

In former constructions the centers of pressure are easily shifted fromtrivial causes. This is a difficulty which my construction overcomes, asplanes made as herea cover or sub-cloth 27 is also used. This is drawnup to the upper cover by some suitable means, such as wires 28, near thefront and rear spars, and the sides of the longitudinal ribs 26 andother wires 29 may also be provided intermediate 'the longitudinalmembers of the frame for a like purpose.

/ In Figs. 7 and 8 T have shown a body 30 formed with intersectingprojecting ribs 31. Suitable material may be pressed or molded into somesuch form in sheets with one or both of its surfaces thus made to formshallow air pockets. Such material may be used for the planes, rudders,propellers, or other parts of the apparatus, or maybe used as a coveringover the material already used for the surfaces.

I have shown the propeller 12 with its pressure surfaces 32 constructedwith air pockets. These may be formed in the ways which I have alreadydescribed, or in' any other desired manner. For example, these surfacesmay be carved, pressed, or molded into the desired shapes. As the bladesof the propellers have a greater rate of movement through the air thando the planes, the pockets may be made shallower than those on theplanes. Y

l have illustrated several forms of my invention to show that I do notlimit myself to any specific construction or arrangement of parts. Ihave particularly pointed out certain elements of anaeroplane ofwellknown design to illustrate the use of my invention, but obviously itis not limited to such parts or to this specific apparatus as it may beused in many. structures in which the surface is used to producepressures or thrusts by the action upon it of an elastic medium. On therudder, blades or other parts of which both sides are used as pressuresurfaces, both of their sides may be made with the air pockets.

What T claim is- 1. An aeroplane having only its under surface dividedinto' a plurality of compartments of substantial. area and depth opendownwardly and closed upwardly and laterally to'increase the thrustagainst the atmosphere relative to the motion of the aeroplane.

2. An aeroplane comprising a frame having transverse ribs, a sheetaflixed to the upper edges of said frame, and ribbon-like membersprojecting edgewise from the under surface of said sheet and afliXed tothe under surface of the sheet and to the sides of the ribs atdiagonally opposed points, to thereby divide the under surface of theaeroplane into a plurality of shallow triangular open pockets.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ELLA LUCK, Ennns'r W. MARSHALL.

